A copy of the proclamation by President Calvin Coolidge creating the Craters of the Moon National Monument. The proclamation includes a map of the boundaries, approximately 39 square miles near Arco, Idaho. The rubber-stamped signature on the...

Spokane Scientist Elsie Hanft (left) kneels in front of a white tepee while a Native American woman and a young girl sit around it, photograph taken during an expedition to Lost Valley, near Craters of the Moon.

A line of pack horses make a half circle as they cross the volcanic soil of the Craters of the Moon area. The horses are barely distinguishable from the rocks on the right side of the photo, about a quarter of the way down from the top.

Printed in Robert W. Limbert's National Geographic article on his expeditions, this is an interior shot of what he called Amphitheater Cave in Craters of the Moon. "This is one of a series of eight caves found near the Bridge of Tears. It is an...

Edward Rhodenbaugh's daily, sometimes hourly, account of activities during the summer break of 1924. As a teacher at Gooding College, Edward had the summer off. He spent his time traveling throughout Idaho and Easter Oregon, including Craters of...

Robert W. Limbert's hand-drawn map of the Cinder Butte Region located near Arco, Idaho. The map includes drawings of wagon roads, horse trails, routes traveled by Limbert, camps, volcanic craters, and a scale.

Five male explorers rest in the cave that explorer Robert W. Limbert named Amphitheater Cave. Limbert described the cave as being "explored for half a mile underground until we came across apparently fresh bear tracks when we turned around and came...